1. Field of the Invention
The present invention is related to a protective circuit for a motor and particularly to a comparison unit associated with a drive unit to avoid the motor producing high instantaneous pulse current and voltage during the motor being started and to avoid the motor and the drive unit occurring high temperature rise to result in damage.
2. Brief Description of the Related Art
Conventionally, coil sets in a motor often produce sparks due to high instantaneous pulse during the motor being started. Referring to FIG. 1, a conventional circuit includes a motor 11, which at least includes a first coil set 120 and a second coil set 111), a drive unit 20, which at least includes a drive IC 210 and a Hall element 220. The drive unit 20 is connected to the motor 11. The Hall element 220 senses magnetic pole change of the rotor in the motor 11 to produce positive voltage H+ and negative voltage H− outputs and the positive and negative voltages H+ and H− outputs are connected to IN+ pin 2109 and IN− pin 2111 of the drive IC 210. The OUT1 pin 2115 is connected to the first coil set 120 and OUT2 pin 2101 of the drive IC 210 is connected to the second coil set 110 so that the motor 10 can be induced to run. However, high instantaneous pulse current and voltage are produced to send the first coil set 120 and the second coil set 110 while the motor 10 is started. Under this circumstance, the temperature of the drive IC 210 and the motor 10 rises quickly and the high temperature is easy to damage the drive IC 210 and the motor 10.